Replace all RegionFile operations with SectorFile

Please see https://github.com/PaperMC/SectorTool
for details on the new format and how to use the tool to
convert the world or how to revert the conversion.

This patch includes conversion logic to convert RegionFiles to
SectorFile on demand. If a SectorFile does not exist, it will
attempt to copy chunk/entity/poi data from existing RegionFiles.

Included in this test patch is logic to dump SectorFile operation
tracing to file `sectorfile.tracer` in the root dir of a world. The
file is not compressed, and it is appended to only. As a result of
the lack of compression, when sending the file back for analysis
please compress it to reduce size usage.

This tracing will be useful for later tests to perform parameter
scanning on some of the parameters of SectorFile:
1. The section shift
2. The sector size
3. SectorFile cache size